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Energy savings

How to calculate your true monthly cost of power

Add up fuel, generator maintenance, grid units and hidden costs to understand what electricity really costs your home or business.

21 August 2026 · 4 min read · Engineering team

Before you can judge whether solar makes financial sense, you need an honest figure for what you spend on power today. Most people underestimate it.

Step 1: Generator fuel

Track fuel purchases for a typical month. If you do not have receipts, estimate:

litres per hour × hours per day × days per month × price per litre

A small petrol generator commonly uses around a litre per hour under moderate load; larger sets use more. Check the hour meter if your generator has one.

Step 2: Generator maintenance

Include oil changes, filters, plugs, servicing and repairs. Spread occasional large repairs over the year.

Step 3: Grid electricity

Add your prepaid unit purchases or postpaid bills. Check your band and tariff on your DisCo receipt.

Step 4: Hidden costs

  • Spoiled food or stock during outages
  • Damaged appliances from voltage fluctuations
  • Lost trading or working time
  • Fuel queues and transport

Bringing it together

The total is your baseline. A solar system’s value is measured against this baseline — not against grid tariffs alone.

Use our energy bill analysis calculator to combine these figures and see an indicative saving.

Next step

Turn reading into a plan.

Book an assessment and an engineer will apply this to your property.

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